Which one of the following biomolecules is correctly characterized?
- Lecithin – a phosphorylated glyceride found in cell membrane.
- Palmitic acid – an unsaturated fatty acid with 18 carbon atoms.
- Adenylic acid – adenosine with a glucose phosphate molecule.
- Alanine amino acid – contains an amino group and an acidic group anywhere in the molecule.
Answer
(1) Lecithin – a phosphorylated glyceride found in cell membrane.
Solution
(1) As per NCERT, some lipids have phosphorous and a phosphorylated organic compound in them; these are phospholipids, found in cell membrane, e.g. lecithin. ⇒ Correct.
(2) Palmitic acid has 16 carbon atoms (including the carboxyl carbon) and is saturated. ⇒ Incorrect.
(3) Adenylic acid is adenosine with a phosphate group (a nucleotide); the sugar is ribose, not glucose. ⇒ Incorrect.
(4) In alanine, the amino group and the carboxyl group are both attached to the same α-carbon, not anywhere in the molecule. ⇒ Incorrect.
Answer: (1)